The long term goal of this project is to increase the number of Donation after Cardiac Death (DCD) livers available for transplantation by developing a new hypothermic machine perfusion (HMP) solution for recovery and preservation. Currently DCD livers are transplantable and have the potential to increase the donor pool 20-40%. However, they are largely under utilized due to poor preservation by the current method of simple cold storage (SCS). Studies show that HMP can improve graft survival in animal models. However, as warm ischemic time is increased, preliminary studies show that the current HMP solution is not sufficient to address the increased stresses of extended warm ischemia. A new solution has been developed to restore depleted energy stores, maintain membrane stability, and minimize oxidation damage. The Phase I project was highly successful in showing that the new HMP solution improved 5hr preservation of extended warm ischemic (60 mins) rat livers in both isolated perfusion and transplant studies. The results showed improved recovery, a reduction in injury, and improved survival (7/9) compared with the UW solution alone (0/6). The main goals of this Phase II SBIR are: 1) to strengthen IP protection, 2) to minimize the potential of toxicity effects, 3) to reduce production costs, and 4) to begin testing the solution in a pre-clinical large animal DCD model. The following Specific Aims will accomplish these objectives: 1) determine the maximum sustainable warm ischemic time for livers to be reclaimed by the new perfusion solution and hypothermic machine perfusion, 2A) optimize the components and 2B) optimize the concentration of components of the new HMP solution, 3) test the new optimized HMP solution in a porcine DCD liver model. To achieve these Aims, isolated perfused liver studies in the rat and porcine and transplant studies in the rat will be utilized. Accomplishing the objectives of this project will strengthen the value of the solution, increase IP protection of the solution, lessen the potential for toxicity issues and form the basis for further testing in a pre-clinical large animal transplant and human ex vivo models in preparation for clinical trials. The success of this project will be directly related to the establishment of a critical partnership between the team of the transplant surgeon, the scientist and biomedical engineer who will collaboratively test and modify as needed the new HMP solution. In addition, HepatoSys, Inc. will collaborate with Organ Recovery Systems to test the new perfusion solution in their prototype Liver Transporter. PUBLIC HEALTH RELEVANCE: Donation after Cardiac Death (DCD) livers have the potential to increase the number of transplants 20-40%, however poor preservation methods and solutions prevent the widespread use of these organs. A new perfusion solution combined with hypothermic machine perfusion preservation has been developed to reclaim these livers that have experienced extended periods of no blood flow after cardiac death. The Phase I SBIR project was highly successful in showing that the new perfusion solution improved recovery and survival in transplant studies. This Phase II project will serve to bring this solution closer to clinical use by optimizing the solution and beginning to test it in large pre-clinical animals that simulate DCD.